I normally just test my reloads at 100m and it's served me pretty well so far although some people recommend testing at longer ranges such as 200 or 300 metres. Which brings me to my point I've just loaded up some new handloads for my 338 Win Mag that I've never loaded for before and someone told me that their 300 win mag shot better at 200m because it took longer for the bullet to "go to sleep".

So do you guys also find this to be true and if so does the 338 Win Mag suffer from the same phenomenon?

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"A free people ought not only to be armed and disciplined, but they should have sufficient arms and ammunition to maintain a status of independence from any who might attempt to abuse them, which would include their own government." -- Unknown author -- Falsely attributed to George Washington --American Legion Rider

The phenomenon of going to sleep depends on bullet design and barrel twist rate more than anything else. This is recovery from initial muzzle exit yaw that results in a helical bullet nose path circling around the trajectory. In normal stabilized bullet flight it is recovered from through progressively smaller radius coning motion of the tip. All else being equal, the faster the rifling twist, the more quickly this recovery occurs for a given bullet; the longer the bullet in calibers, the more slowly it occurs for a given twist.

If the gyroscopic stability factor of the projectile is greater than one, it eventually goes to sleep. If it is less than one, it gradually grows until bullet tumbles. If it is 1.0 exactly, the coning motion neither grows nor shrinks. While there is some disagreement, most ballistics authorities think the best gyroscopic stability factor will lie somewhere between 1.4 and 1.7 for maximum accuracy. You can use the stability estimator on the JBM site (scroll down to the bottom of the calculator page) to get an estimate of stability factor.

In general, flat base bullets will yaw less at the muzzle than boattails because the base dwells in the high speed muzzle blast between the bullet and crown at exit for a shorter time. They also have more bearing surface in a given weight than a boattail for easier bore alignment. So, it is easiest to get shorter range accuracy from a flat base bullet. Usually I expect a flat base to shoot tighter up to around 200 yards. By 300 yards the wind begins to have more apparent effect and the boattails have mostly gone to sleep and start to show the advantage of their higher ballistic coefficients in fighting wind. In one extreme example, though, Walt Berger says the current long 155 grain boattail Palma bullets, fired in the slow 13.5" twist Palma barrels, can take up to 500 yards to go to sleep, and he recommends his 150 grain flat base over them up to that range. That is unusual, though.

So, the answer to your question depends on the bullet and the barrel and the intended shooting range. I think, in general, if you have the range available, always test at both the longest and shortest ranges you will use. If I had to pick just one range, 300 yards seems to me a good compromise for rifle loads, not just because of drift, but also because it is long enough to begin to see a little vertical stringing due to muzzle velocity spread. That is often invisible at 100 yards and not yet clear enough at 200.

For handguns, the same rule of thumb about using the ranges you will shoot applies. Conventional pistol matches shoot slow fire at 50 yards, so that's the key range for match pistols. For defensive shooting, seven yards is not an undisputed average gunfight range but is a commonly accepted one, so using a little over twice that, or the common 50 foot range, makes sense to be able to stay on a pie plate with. For centerfire silhouette handguns, you might want test at 200 yards in case you happen onto a long range pistol silhouette match to shoot in.

I guess it depends on the "test". For initial load development, 100 yards, mostly because that's max range at my most convenient range location. Eventually though, as UncleNick said, you're going to have to "test" them at whatever maximum range that you intend to shoot. I wouldn't want to sight in at 100 yards and never shoot farther but then try to shoot a deer at 400 yards.

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Still happily answering to the call-sign Peetza.
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The problem, as you so eloquently put it, is choice.
-The Architect
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He is no fool who gives what he can not keep to gain what he can not lose.
-Jim Eliott, paraphrasing Philip Henry.

My reloading partner and I have the benefit of having our own "home" range. We have 50, 100, and 260 yard ranges. I can tell you that what you think is the next sliced bread at 100 yards can really have you scratching your head at 260. I hunt with a 44 mag handgun and shoot it from a rested position at 100 yards quite a bit.

When I'm doing load development I always do it at 100 yards mainly because I don't have to walk as far to change targets because there will be a lot of targets. Once I decide I have the ultimate load for that cartridge and I will be using it to hunt with, sure I'll shoot a few at 200 yards. For handguns I shoot at 25 yards for most calibers except for my 454 or 480 which I shoot at 50 yards usually and occasionally even try a 100 yard target sometimes with them.

100yds for initial rifle development, 300 for any long range loads. I seldom test generic hunting ammo (30/30 for example) at that range however,since I hunt eastern woodlands. I just sight 1.5-2" high at 100 and am good to any range I'll likely see for big game.

For handguns, I typically test at 50ft, except for hunting handguns where I develop at 25yds and final test at 50yds.

For shotguns it's 50yds and 100yds for slugs and 25 only for birdshot/buckshot loads.

For new semi-auto pistol load development, I shoot a few rounds at 7 yards to get a feel for the load. Once I am happy with the load (tight shot groups around 1"), then I move my target out to 10 and 15 yards.

I test loads like I shoot USPSA stages - off hand. For me, testing shot groups beyond 10-15 yards are too much affected by the shooter's grip and trigger jerk/push to ascertain whether inconsistent shot groups are due to the load or shooter.

I only test shot groups at 20-25 yards after I got consistent repeatable shot groups at 10-15 yards.

Here's a recent range test I posted at THR of 200 gr SWC with 4.0 gr of Promo (4.5" M&P45 with a trigger job). It did not produce as tight of shot groups as my reference 5.0 gr of W231/HP38, but it was my first testing - The W231/HP38 load produces similar groups at 20-25 yards.

Rifles: 90-115 yards (Depends where we are, and what's available - always middle-of-the-desert improvised ranges). Rarely, do we have the ability to shoot farther than that, safely (too many military installations and bombing ranges).

Pistols: about that far... (7-50 yards - I don't get very serious about pistol accuracy).

__________________"Such is the strange way that man works -- first he virtually destroys a species and then does everything in his power to restore it."

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